Components of computing devices that consume electrical power, such as logic devices and memory devices, also generate heat during operation. Certain heat-generating components, such as logic devices (e.g., memory controllers, central processing units (CPUs), graphics processing units (GPUs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs)), emit far more heat than other components such as memory, and such excess heat may compromise operation and shorten the life of both types of components. Heat management techniques for the heat-generating components of computing devices may generally include thermally coupling a heat sink to a heat-generating component (e.g., using a thermal interface material), providing air flow over and around the heat-generating component (e.g., using a fan), or thermally coupling a liquid cooling apparatus to the heat-generating component. In solutions employing air cooling, a duct may be provided to direct the airflow along a desired flow path.
Specific thermal management problems arise in the case of servers comprising CPUs and multiple memory modules, such as dual in-line memory modules (DIMMs) each comprising multiple DRAM chips and buffer memory. When unconstrained cooling air flow is directed over one or more CPUs directionally followed by multiple, vertically extending memory modules, a significant volume of air flows over, rather than between, the memory modules, negating much of the effect of high power cooling fans. In another common server configuration, two banks of vertically extending memory modules flank one or more CPUs. Air flow directed by one or more cooling fans parallel to the memory modules flows primary in the corridor between the banks of memory modules and over the one or more CPUs, again largely negating the effect of high power cooling fans.
The use of a single duct extending over memory modules to constrain air flow to a volume immediately surrounding the memory modules and between the memory modules, issues of excessive memory operating temperatures remain. Such issues arise from limitations in using conventional single air duct configurations. To improve cooling capability using a single air duct, higher air speed is required. However, there are at least two problems associated with higher air speeds. First, when air speed is relatively low, for example less than two m/s, a slight increase in air speed can dramatically improve thermal performance. However, when the employed air speed is already relatively high, for example greater than about three m/s, the effect of air speed on cooling performance becomes ever-more negligible as air speed increases. Further, higher speed requirements dictate more power consumption from the fans and more noise from the cooled system.